Protection of superconducting wires and cables used in high power/high field applications

超导材料具有在给定的临界电流(IC)和临界温度(TC)以下携带无损直流电流的独特性能。本提案中考虑的超导体被称为高温超导体(HTS)，因为它们在液氮温度以上表现出超导电性，即77K(-196oC)，这是一种廉价的冷却剂，在电力设备等大规模应用中是负担得起的。HTS线材呈扁平带状，可以携带惊人的高电流密度，例如在77K时为&gt；2 mA/cm2。它们是高场电磁铁等应用的完美选择，可以达到前所未有的场值，例如在4K时最高可达50T。这可能会改变高分辨率磁共振成像(MRI)、核聚变、粒子加速器等领域的游戏规则。此外，由于磁体通常需要数百公里的HTS带材，它们有望在不久的将来成为扩大HTS线材生产和降低成本的巨大市场“驱动力”。超导设备最大的挑战是可靠地保护它们免受可能迅速摧毁它们的热不稳定性的影响。在这项建议中，我们建议扩大在我的研究小组内发现的一个概念的应用范围，这个概念被称为“电流分流器”(CFD)。这一概念允许在热不稳定发生时将其传播速度加快一个数量级，从而大大简化了对HTS设备，特别是HTS磁体的保护。它被视为该学科的潜在突破，因此在短期内值得认真考虑。该技术于2015年5月获得美国专利，短期研究可能会产生进一步的知识产权，如果它渗透到核磁共振市场，潜在的广阔市场。*在这个项目中，将追求以下主要目标：*1)找到一种有效且经济的方法来在商业HTS磁带的长长度上实施电流分流(CFD)概念*2)了解由许多HTS磁带(例如Roebel或TASC电缆)在各种实验条件下形成的大电流电缆中热点成核的影响*3)评估使用CFD概念与最先进的高温超导磁体保护系统相结合的影响*这些目标与我的研究计划的最终目标一致，这是为了“允许出现新一代紧凑和高效的超导装置，以提高电力系统的供电安全性，并使高场高温超导磁体出现”。*该项目计划培养3名博士生、5名硕士研究生和5名暑期实习生。该项目的某些部分将与国际合作伙伴一起开展，以利用现有基础设施并加快研究成果的产生。*

Superconducting materials have the unique property of carrying lossless DC currents below a given critical current (Ic) and critical temperature (Tc). Superconductors considered in this proposal are called “High Temperature Superconductors” (HTS), because they exhibit superconductivity above liquid nitrogen temperature, i.e. 77 K (-196oC), a cheap coolant that is affordable in large-scale applications such as power devices. HTS wires come in the form of flat tapes and can carry amazingly high current densities, e.g. >2 MA/cm2 at 77 K. They are perfect for applications such as high field electromagnets, which allow reaching unprecedented field values, e.g. up to 50 T at 4 K. This could be a game changer in high-resolution magnetic resonance imaging (MRI), nuclear fusion, particle accelerators, etc. Also, since magnets typically require hundreds of kilometers of HTS tapes, they are expected to be the big market “driver” sought for scaling-up the production and reduce costs of HTS wires in a near future. The biggest challenge with superconducting devices is to protect them reliably against thermal instabilities that can destroy them rapidly. In this proposal, we propose to expand the application range of a concept discovered within my research group and that is called “current flow diverter” (CFD). This concept allows speed-up by an order of magnitude the propagation of a thermal instability when it occurs, which considerably simplifies the protection of HTS devices, in particular HTS magnets. It is seen as a potential breakthrough in the discipline, and therefore deserves serious consideration in the short term. The technology was awarded a U.S. patent in May 2015, and further I.P. could arise form short-term research, with potentially wide market if it penetrates the MRI market.***Within this project, the following main objectives will be pursued:***1) Find an effective and economical approach to implement the current flow diverter (CFD) concept on long lengths of commercial HTS tapes***2) Understand the impact of a hot spot nucleation in high-current cables made of many HTS tapes (e.g. Roebel or TASC cables) under various experimental conditions***3) Evaluate the impact of using the CFD concept combined with state-of-the-art protection systems for HTS magnets***These objectives are aligned with the ultimate goal of my research program, which is to “allow the emergence of a new generation of compact and efficient superconducting devices for improving security of supply in power systems and enable the emergence of high field HTS magnets”.***Along the project, it is planned to train 3 Ph.D. students, 5 Master's student, and 5 summer interns. Some parts of the project will be carried out with international partners in order to take advantage of existing infrastructures and speed-up the generation of research results.********* *** *** *** *** ******************************************